Heretofore, a semiconductor manufacturing device, a liquid crystal panel manufacturing device, and others use such a chemical liquid valve as disclosed in Patent Literature 1, for example. A chemical liquid valve is a fluid control valve arranged to bring a valve element into or out of contact with a valve seat placed between an inlet port and an outlet port to control the flow of chemical liquid or solution from the inlet port to the outlet port. FIGS. 13 and 14 are sectional views of the chemical liquid valve disclosed in Patent Literature 1.
As shown in FIG. 13, a chemical liquid valve 101 includes: an actuator core part having a cylinder 110, a valve element 142, a piston 143, a spring 141 and others; an engagement part 120 closing an opening of the cylinder 110; a body 130 having a valve seat 131, an inlet port 132, an outlet port 133 and others; and a mounting plate 150 for fixing the chemical liquid valve 101.
In the chemical liquid valve 101, the valve element 142 is moved up and down with respect to the valve seat 131 by action of an urging force of the spring 141 such as a coil spring and the pushing force of pressurized operation air AR which will act in an opposite direction to the urging force.
In the actuator core part, the piston 143 connected with the valve element 142 is slidably mounted in the cylinder 110. The spring 141 is placed on a support surface 143a of the piston 143 on an opposite side from a pressure-receiving surface of the piston 143 which will be subjected to the operation air AR. The spring 141 is placed with its both ends being supported on the support surface 143a of the piston 143 and a support surface 126a of the cover 120 that closes the opening of the cylinder 110, so that the spring 141 urges the valve element 142 toward the valve seat 131 by its spring force.
The cover 120, the actuator core part, the body 130, and the mounting plate 150 are stacked and assembled integrally for manufacture of the chemical liquid valve 101. Specifically, as shown in FIG. 14, first bolts 160 inserted through the cover 120 are tightened against the mounting plate 150 through the cylinder 110 and the body 130 to fix them.
The chemical liquid valve is assembled not only for manufacture. For example, the chemical liquid valve disassembled for maintenance after use is assembled again. In a disassembling work, the pushing force of operation air is not applied to the valve element 142, so that the valve element 142 is in contact with the valve seat 131 by the spring force. In this state, when the first bolts 160 tightened against the mounting plate 150 are loosened one by one, the actuator core part is apt to incline with respect to the body 130, pressing the valve seat 131, causing plastic deformation of the valve seat 131.
To protect the valve seat 131 and others during disassembling, Patent Literature 1 shows the structure that a pin 115 is inserted in an indicator 145 during disassembling, as shown in FIGS. 13 and 14, the valve element 142 is forcibly held apart from the valve seat 131 to improve workability in the disassembling work.